Wilms’ Tumor

Despite being able to ignore many odd occurrences in the house, there are several things that will classically attract acute attention from a parent: fever; a child “not eating;” not pooping for a day; lumps and bumps; and rashes. The bathtub happens to be a common environment that the last two are first detected. Historically, physicians even used “bathtubs” to feel for intra-abdominal masses. Let us take a minute to review a significant abdominal mass that a parent may first detect with the assistance of bath time – Wilms’ Tumor:

Wilms’ Tumor: Basics

  • Wilms’ Tumor (nephroblastoma) is common! [Servaes, 2019; Szychot, 2014]
    • It affects 1 in 10,000 children!
    • Accounts for ~5% of ALL childhood cancers.
    • Accounts for ~80% of all pediatric renal tumors.
  • Most commonly encountered in younger children. [Servaes, 2019; Szychot, 2014]
    • 95% of cases occur in children < 10 years of age.
    • Vast majority diagnosed before age of 5.
    • It can rarely, however, occur in older patients and adults.
  • A predisposing genetic syndrome is associated with ~5% of Wilms’ Tumor patients: [Szychot, 2014]
    • Several well defined genes play a role in Wilms’ Tumor like:
      • WT1 gene
      • WT2 gene
      • WTX gene
    • These can be found concurrently in other genetic syndromes:
      • WAGR syndrome (Wilms’ tumor, Aniridia, Genitourinary (GU) abnormalities, and mental Retardation)
      • Beckwith-Wiedemann syndrome
      • Denys-Drash syndrome – GU abnormalities, and nephropathy, hypertension
      • Frasier syndrome – Focal glomerular sclerosis, kidney failure, and gonadal dygenesis
      • Simpson-Golabi-Behmel syndrome
    • Children with genetic syndromes linked to Wilms’ tumor are screened routinely during your childhood.
  • Overall survival is > 90%! [Servaes, 2019]
    • Unfavorable characteristics include:
      • Unfavorable histology and molecular markers
      • Bilateral disease
      • Relapse
    • Classification plays a role in management and prognosis.
      • Classification differ between Children’s Oncology Group (COG) and International Society of Pediatric Oncology (SIOP).
      • Management decisions (ex, immediate nephrectomy vs pre-surgical chemotherapy) also differ between the groups, but outcomes are similar.

Wilms’ Tumor: Presentations

  • The majority of patients will present with an “asymptomatic abdominal mass.” [Szychot, 2014; Erginel, 2014]
    • Often described by parents as being found during bathing.
    • Also noted as a protuberant abdomen at times.
    • Mass is typically firm.
  • ~20-30% will complain of abdominal pain. [Szychot, 2014]
    • The tumor itself can cause mass effect on other adjacent structures.
    • Tumor may not, itself, be tender on palpation.
  • Tumors may also present in ExtraRenal sites [Rojas, 2013]
    • Many case reports of Wilms’ occur outside of the kidney with no kidney involvement.
    • Can be found in:
      • Bladder
      • Inguinal area
      • Vagina
      • Ovary
      • Lumbar paraspinal area
      • Coccyx
      • Retroperitoneum
  • Presentations may also be of known complications: [Szychot, 2014]
    • Uncommon (<10% of cases), but can be severe.
    • Acute Abdomen
      • Rapid tumor enlargement
      • Anemia
      • Hypertension
      • Fever
      • May have associated tumor rupture
    • Tumor Extension into adjacent vascular structures.
      • ~11% of cases involve vascular extension.
      • Thrombus also can occur – ~4%
      • Renal Vein and Inferior Vena Cava involved.
      • May lead to:
  • Late Effects / Complications [Servaes, 2019; Szychot, 2014]
    • The “cost of cure” can be high in survivors of Wilms’ tumor.
    • Anthracycline (ex, Doxorubicin) therapy can lead to Heart Failure.
    • Pulmonary fibrosis can occur from lung radiotherapy.
    • Secondary malignant neoplasms can develop:
      • Sarcomas of bone and soft-tissue
      • Breast cancer
      • Leukemia
      • Lymphoma
      • Melanoma

Wilms’ Tumor: Initial Evaluation

  • Abdominal Ultrasound is the 1st imaging modality. [Servaes, 2019; Szychot, 2014]
    • Characterizes the mass.
    • Defines the location and extent of involvement (both kidneys?).
    • Determines whether vascular invasion or clot formation is present.
    • Checks liver for metastases.
  • CT and/or MRI of the abdomen [Servaes, 2019; Szychot, 2014]
    • Both are considered reasonable to use to further evaluate once renal tumor is detected.
    • MRI may be preferred if both kidneys are involved.
  • Chest imaging. [Servaes, 2019; Szychot, 2014]
    • The lungs are a common site of metastatic spread.
    • 10 – 20% will have lung involvement at time of diagnosis.
    • CXR is usually the initial study performed in the ED.
    • CT will often be done as well.

Moral of the Morsel

  • The Bath – a great place for parents to detect pathology!
  • It isn’t constipation. A painless abdominal mass in a previously healthy child can be the presentation of Wilms’ tumor.
  • Check the Ultrasound! But, don’t forget about the lungs!


Servaes SE1, Hoffer FA2, Smith EA3, Khanna G4. Imaging of Wilms tumor: an update. Pediatr Radiol. 2019 Oct;49(11):1441-1452. PMID: 31620845. [PubMed] [Read by QxMD]
Szychot E1, Apps J1, Pritchard-Jones K1. Wilms’ tumor: biology, diagnosis and treatment. Transl Pediatr. 2014 Jan;3(1):12-24. PMID: 26835318. [PubMed] [Read by QxMD]
Erginel B1, Vural S, Akın M, Karadağ CA, Sever N, Yıldız A, Tanık C, Demir AA, Yanar O, Dokucu Aİ. Wilms’ tumor: a 24-year retrospective study from a single center. Pediatr Hematol Oncol. 2014 Aug;31(5):409-14. PMID: 25007381. [PubMed] [Read by QxMD]
Rojas Y1, Slater BJ, Braverman RM, Eldin KW, Thompson PA, Wesson DE, Nuchtern JG. Extrarenal Wilms tumor: a case report and review of the literature. J Pediatr Surg. 2013 Jun;48(6):E33-5. PMID: 23845655. [PubMed] [Read by QxMD]
Buckley KS1. Pediatric genitourinary tumors. Curr Opin Oncol. 2012 May;24(3):291-6. PMID: 22476187. [PubMed] [Read by QxMD]
Davenport KP1, Blanco FC, Sandler AD. Pediatric malignancies: neuroblastoma, Wilm’s tumor, hepatoblastoma, rhabdomyosarcoma, and sacroccygeal teratoma. Surg Clin North Am. 2012 Jun;92(3):745-67, x. PMID: 22595719. [PubMed] [Read by QxMD]
Davidoff AM1. Wilms’ tumor. Curr Opin Pediatr. 2009 Jun;21(3):357-64. PMID: 19417665. [PubMed] [Read by QxMD]


Sean M. Fox
Sean M. Fox
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